Download Gaydos - MAMEF for POCT for CT

Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF)
Point of Care Test for the Detection of Chlamydia trachomatis
Gaydos CA1, Melendez JH2, Jett-Goheen, M1, Huppert, J3, Geddes CD2
Poster 652
1Div
Infectious Disease, Medicine, Johns Hopkins University Medical School , Baltimore Maryland,
2Institute of Fluorescence and Department of Chemistry and Biochemistry, University of Maryland
Baltimore County, Maryland 3 Cincinnati Children's Hospital Center, Cincinnati, Ohio, USA
Background
Chlamydia trachomatis (CT) is the most prevalent bacterial
sexually transmitted infection (STI) reported to the U.S.
Centers for Disease Control and Prevention. Accurate point-ofcare diagnostic tests are urgently needed for rapid treatment of
patients. To address this need, we have developed and tested a
Microwave-Accelerated
Metal-Enhanced
Fluorescence
(MAMEF) assay. We report assay use on clinical samples.
Methods:
MAMEF combines metal enhanced fluorescence (MEF) and
Microwave Acceleration (MA). A variety of transport buffers
and media were investigated for compatibility with the MAMEF
method. Deionized water, followed by centrifugation, was the
most suitable buffer for re-hydration of dry swabs and
subsequent lysing and MAMEF. Archived vaginal swabs that
were dry-transported were tested. First 45 samples were
preselected to have mostly positive nucleic acid amplification
test (NAAT) results. Second set of 125 swabs were randomly
selected. MAMEF results were compared to results from
Aptima Combo2 or ProbeTec (NAAT) results as the reference
method.
Results
It is estimated that as few as 10 IFU/mL of CT can be
detected in less than 10 minutes total time, including
the sample preparation time.
The MAMEF assay
correctly identified 36/45 (80%) NAAT-positive samples,
and 116/125 (92.8%) of the NAAT-negative samples.
Table. Comparison of MAMEF to NAATs
N = 170 vaginal swabs
ASSAY
Probe Tec Probe Tec
or Combo2 or Combo2 Total
+
-
MAMEF + 36
9
45
MAMEF - 9
116
125
Total
125
170
45
Sensitivity = 80%
Specificity = 92.8%
Swab Prevalence = 45/170 = 26.5%
Demographics of study participants
Metal-Enhanced Fluorescence (MEF)
Increased Luminescence; Improved Lumophore
Photostability; Lysing Triangles
Microwave Accelerated (MA)
Low power microwave heating – reduces assay run time
Age (Yr)
14
15
16
17
18
19
20
21
26
Percentage
3.4%
4.7%
8.8%
15.5%
19.6%
16.9%
19.6%
10.8%
0.7%
Conclusions
The CT MAMEF assay demonstrated high
sensitivity and specificity when using vaginal
samples transported as dry swabs. MAMEF
platform is a significant step forward in the
development of a point of care test for CT.
Bibliography
Zang Y, Agreda P, Kelly S, Gaydos C, Geddes CD. Development of
a microwave-accelerated metal –enhanced fluorescence 40
second, 100 cfu/mL point of care assay for the detection of
Chlamydia trachomatis. IEEE Trans BioMed Eng 58:781-784,
2011.